The present invention relates to a wiper ring for removing debris from the surface of the rod of a mechanical pump as the rod is retracted into the pump.
In a typical mechanical pump jack, a hydraulic (or Pneumatic) actuator builds or relieves a fluid head in a cylindrical pump chamber, which drives the piston-like pump rod along a Pump longitudinal axis. The pump is sealed from the environment at a pump gland which is mounted at the end of the pump housing and through which the rod is driven, with the far end of the rod extending outside of the pump.
There are two primary sealing tasks in such equipment. First, the pump fluid must be sealed within the pump. Accordingly, a piston ring is mounted in the gland and the rod extends through the piston ring to seal the fluid in the pump chamber. But equally as important, foreign material (dirt, abrasives, dust, fluids) must be prevented from entering into the pump. Such contaminants can cause fouling and corrosion within the pump, can cause scoring of the rod itself, and can reduce the life of the rod, rod bushings, and the piston seals.
As to the latter sealing task, typically a wiper ring whose OD is captured within a receiver groove on the ID of the gland is provided to exclude contaminants carried on the rod from entering into the pump. The top of the wiper ring includes a wiper lip which cleans the foreign material off of the surface of the sliding rod as it retracts into the pump. However, the portion of the wiper ring contacting the rod puts a drag on the rod, and too much drag can cause the ring to bind to the rod and pull away from and even roll out of the gland's receiver groove. Ideally this drag is minimized while wiping is maximized.
As to the former sealing task, if hydraulic fluid escapes past the piston seal, then the system pump pressure can be developed on the underside of the wiper ring which will likely cause the ring to blow out of the pump jack entirely. Therefore it is important to maintain the seal between the piston ring and rod. And it is also important to exclude abrasive contaminants which otherwise tend to build up on the back side of the piston ring and can cause scoring and excessive wear between the piston ring and rod.
It is therefore an object of the present invention to provide a wiper ring with improved sealing capability and reduced drag.
It is another object of the present invention to provide a blow-out resistant wiper ring with improved sealing capability and reduced drag.